Screw hole with preinstalled screw

Abstract

The present invention relates to a screw hole (12) in hardware parts (10), especially in metal furniture hardware, in which is screw with a given outside thread diameter provided with a truncoconical countersink head can be preinstalled. The hole (12) has a countersink (18) matching the truncoconical head of the screw, followed by a substantially cylindrical hole section (20) for the passage of the shaft of the screw. The inside diameter of the cylindrical hole section (20) is slightly smaller than the outside diameter of the screw shaft measured across the threads of the screw (14), and into the cylindrical hole section an internal thread (24) is worked into the cylindrical hole section, where the length of the threaded shaft as measured in the screw driving direction is shorter than that of the unthreaded shaft section of the screw adjoining the bottom of the countersink head.

I claim: 
     
       1. A screw hole (12) in hardware pieces (10), having a preinstalled screw provided with a truncoconical countersink head (16) and having a threaded shaft section (22) of given outside thread diameter (d 1 ) and a threadless shaft section (28) between the countersink head and the threaded shaft section, the diameter (d 2 ) of which is smaller than the diameter of the threaded shaft section, the screw hole (12) having a countersink (18) of a shape complementary to the truncoconical countersink head (16) of the screw and having a substantially cylindrical hole section (20) disposed adjacent in the countersink for the passage of the shaft of the screw: comprising said cylindrical hole section (20) having an inside diameter (D) that is slightly smaller than an outside diameter (d 1 ) of the screw shaft measured across the threads of the screw (14) and slightly greater than the diameter (d 2 ) of the threadless shaft section (28), and said cylindrical hole section (20) having an internal thread section (24) that receives the threaded shaft (22) of the screw (14) in the preinstalled state, wherein said internal thread section (24) has a length (L) measured in a driving direction which is shorter than length (1) of the threadless shaft section (28) of the screw (14),and wherein the depth of the threads of the internal thread section (24) in the cylindrical hole section (20) is smaller than the height of the threads of the threaded shaft section (22) of the screw (14).   
     
     
       2. The screw hole according to claim 1, wherein the threads in the internal thread section (24) of the cylindrical hole section (20) are so configured that the threads of the threaded shaft section (22) of the pre-installed screw (14) are held in the hole (12) with a light force fit. 
     
     
       3. The screw hole according to claim 1, wherein a short hole section (26) expanding in diameter adjoins the end of the substantially internal thread section (24) opposite the countersink (18), and its diameter (D 1 ) at the bottom side, remote from the countersink, is approximately equal to or slightly greater than the outside diameter (d 1 ) of the shaft of the screw (14). 
     
     
       4. The screw hole according to claim 1, wherein the internal diameter (D) of the hole (20) is smaller than the outside diameter (d 2 ) of the unthreaded section (28) of the shaft of the screw (14).